Photocopying and transfer process involving photopolymerization



United States Patent 3,234,021 PHOTOCOPYING AND TRANSFER PROCESS INVOLVING PHOTGPOLYMERIZATION Andre K. Schwerin, deceased, late of Binghamton, N.Y., by Johanna Schwerin, administratrix, Binghamton, N;Y., and Steven Levinos, Vestal, and Fritz W. H. Mueller, Binghamton, N.Y., assignors to General Aniline & Film Corporation, New York, N.Y., a corporation'ofDelaware No Drawing. Continuation of application Ser. No. 783,715, Dec. 30, 1958. This application Oct. 15, 1962, Ser. No..230,760.

Claims. (Cl. 9628) This application is a continuation-in-part of application Serial No. 731,538 filed April 28, 1958, and a continuation of'Serial' No. 783,715v filed December 30, 1958, both now abandoned.

The present invention relates to a photographic copying. and transfer process for the reproduction. of printed matter and, more particularly, to such a process in which a ph-otopolymerization system is utilized.

There are a number of well-known methods of reproducing printed matter while using differentially hardened silver salt emulsion layers and transferring unhardened strata of such layers to a support preferably paper. In general, the so-called reflex copy method is used by which anemulsion layer is exposed through its support and a positive image is obtained from a document or other printed matter. Such procedures are disclosed, for example, in US. Patents 2,592,368, 2,596,756, 2,716,059 and German Patent 1,015,313.

The prior methods are based on the employment of light-sensitive, substantially unhardened silver halide emulsions which after'exposure undergo differential hardening by subjecting them to a' gelatin tanning silver halide developer such as pyrocatechol, 3,4-dihydroxy-diphenyl- 2,5-dihydroxy-diphenyl or the like. In some of these methods, the developing agent and a dye-forming component are incorporated in the emulsion so that upon development, diiferential hardening and dye formation take place in the processed emulsion. these methods lie in the fact that they depend upon the conjoint use of silver halide emulsions and processing solutions, the latter being subjected to temperature control and progressive exhaustion.

We have now devised a simple method for producing positive prints by a transfer process in. which a polymerizable vinyl monomer and a light-sensitive polymerization catalyst are coated in a colloidal carrier onto a base such as paper, film or the like, the coating exposed reflexwiseto a suitable subject and after slight moistening, sqeegeed against another support such as paper to effect transfer to the second support of the unpolymerized portions of the exposed coating. The portions of thecoating which are transferred may then be hardened by further photopolymerization and/ or by treating with a coloring material to improve contrast.

The reproduction of images, particularly printed matter, by such method and the materials for use therein constitute the purposes and objects of our. invention.

In our procedure, a coating is made, for example, on paper, consisting of a vinyl monomer such :as acrylamide and a cross-linking agent such as N,N-methylene-bisacrylamide to which is added a certain amount of a colloidal carrier such as gelatin and a light-sensitive photopolymerization catalyst such as a water soluble silver salt, i.e.,, silver nitrate. The above compounds are dissolved in water and the solution coated to a thickness of 5 to mu on a suitable translucent support such as paper.

The paper bearing the coating is brought into intimate contact with the document to be reproduced and ex- The disadvantages of "ice posed reflexwise with an incandescent light source, i.e., through the support bearing the coated emulsion. After exposure, the surface of the coating is moistened slightly, for instance by exposing the coating for a few seconds to a fine stream of water vapor, and it is then placed firmly against a transfer paper which may be any ordinary white paper with a slightly roughened surface. After a few seconds the papers are separated and it will be found that strata of the unpolymen'zed parts of the coating or emulsion are transferred to the second paper. The

unpolymerized transferred material may be exposed fur-- tlier to cause it to photopolymerize to a hardened mass. After renewed moistening of the coating, the transfer process may be repeated several times.

In order to obtain a visible contrasty image on the transfer paper, either the coating or the transferred resist'may be dyed with a water soluble dark ink by bathing or roller-inking. In such case, the transfer paper should have a water repellent surface coating such as of wax to prevent penetration of the ink into the paper fibers.

Preferably, however, We secure tone separation by use in the emulsion coating of a compound which after transfer to the receiving paper is capable of giving a blueblack, print-out image. To this end, we use silver iodide either as the catalyst for photopolymerization or in addition to the catalyst. The transfer sheet when silver iodide is employed should contain a sensitizer for silver iodide such as monomethyl-paminophenol sulfate, 0-, mor p-dihydroxybenzene, 4-amino-6-sulfo-a-naphthol or the like. Upon exposure to light, the resist transferred from the coating and containing silver iodide becomes blue-black due to the print-out effect of the transferred silver iodide in contact with the sensitizer.

It is also preferable to enhance the differential between the polymerized and unpolymerized parts of the negative emulsion by adding a small amount of a gelatin hardening substance such as chrome alum to the negative emulsun.

In lieu of the acrylamide mentioned as the vinyl monomer, We may use any other polymerizable vinyl compound whether water or solvent soluble, i.e., in acetone, butyl acetate, alcohol or the like. Illustrative of such monomers are acrylonitrile, N-hydroxyethyl acryl-amide, methacrylic acid, acrylic acid, calcium acrylate, methacrylamide, vinyl acetate, methylmethacrylate, methylacrylate, ethylacrylate, vinyl benzoate, vinyl pyrrolidone,

vinylmethyl, ether, vinyl'butyl ether, vinylisop-ropyl ether, vinyliso-butyl ether, vinylbutyrate, butadiene or mixtures of ethylacrylate with vinyl acetate, acrylonitrile with styrene, butadiene with acryl-onitrile and the like. We have ascertained that any one ofthese monomers when employed in our process is sufliciently hardened in the presence of a photopolymerization catalyst so as to permit transfer of unpolymerized material without transfer of the polymerized material.

Cross-linking agents such as the N,N-methylene'-bisacrylamidepreviously mentioned serve to increase the molecular'weight and hence the physical hardness of the polymer obtained by photopolymerization. The use of the cross-linking agents is, therefore, recommended and for this purpose we utilize an unsaturated compound containing at least two terminal vinyl groups each linked to a carbon atom in a straight chain or in a ring, of which N,l l'-methylene-bis-acrylamide is an example. Other agents which may be employed are those described, for example, by Kropa and Bradley in Vol. 31, No. 12, of Industrial and Engineering Chemistry, 1939. Among such cross-linking agents may be mentioned triallyl cyanurate, divinyl benzene, divinyl ketones and diglycol-diacrylate. Uusually the cross-linking agent is employed in for our purposes.

' jector, 7' distance, 20 seconds).

an amount ranging from 10 to 50 parts of monomer to each part ofthe cross-linking agent.

Many varieties of photopolymerization catalysts may be employed. Thus, we may use radiation-sensitive silver salts as described in the application of Steven Levinos, Serial No. 715,528 filed February 17, 1958, now USP 3,075,907; silver salt emulsions such as described in the application or" Steven'Levinos and Fritz W.H. Mueller,

Serial No. 731,538, now abandoned filed April 28, 1958; mixtures of silver compounds and amphoteric metal oxides as described in the application of Steven Levinos and Fritz W. H. Mueller, Serial No. 765,275 filed October 6, 1958, now USP 3,050,390; and mixtures of silver compounds as described in the application of Steven Levinos,

Serial No. 765,958 filed October 8, 1958, now USP 3,053,- 745; light-sensitive organic peroxides such as light-sensitive di-tertiary butyl peroxide; light-sensitive diazonium compoundssuch as those described in U .8. Patent 2,471,-

959 granted May 31, 1949;. benzoquinone; zinc oxide or titanium dioxide alone or in admixture (1) with salts of amides, or (3) with amino fluorimes, hydroxy' fiuorimes or hydroxy fluorones in which the unsaturated carbon atom linking the two benzo rings is substituted by a phenyl.

mercury, thallium and iron, (2) with organic oxidizable carboxylic acids, salts thereof, aldehydes, phenols and radical and thiazines. Any of these photopolymerization catalysts when used in catalytic amounts, say from about .5 to 25% by weight if the monomer, will be adequate are employed alone or with the, aforesaid promoters,

When zinc oxide or titanium dioxide amounts of the oxides as high as double the weight of the monomer are effective. The zinc oxide or titanium dioxlde systems are disclosed in the applicationof Evans,

Mueller and Levinos filed of even date herewith, entitled 5 Oxides as Catalysts, Serial No. 783,725, now U.S. Patent Photopolymerization of Vinyl Monomers 'With Metal The coating of the negative emulsion containing the monomer and photopolymerization catalyst includes a colloidal carrier in which the monomer and catalyst are dispersed. These carriers, usual in photography, will be gelatin, polyvinyl alcohol, carboxymethyl cellulose, casein or the like. p

The advantages which are inherent in our invention are believed toabe apparent. Thus, instead of the exposure,

developing and transfer steps of the prior art'methods which are based on photographictanning, only an exposure and transfer step are needed. No subsequent or inter-mediate, washing steps are necessary and no conjoint use of silver halide emulsions and processing :solutions are required to directly produce the positive image trans- After drying, the paper is brought in contact with a copy method) to an active light source (500 watt pm: After exposure, the surface of the paper is slightly moistened with ,a fine sprayof water vapor and brought immediately in contact 7O printed matter .and exposed through its support (reflex i with a transfer paper (ordinary paper'with a slightly rough. surface). A rubber roller is applied firmly "over the sandwich and after a few seconds both papers are separated. x On thetransferpaper a brownish colored positive resist is retained, due to the partial transfer of thereduced silver nitrate from.the negative emulsion; Clear, sharp lines and letters are obtained.

Example: II. The following coating formula is used for the negative emulsion; V

A m g 15 10% inert gelating 30 Titanium dioxide g 4 Rose Bengal mgc- 8 V 10% Chrome alum ml 0.5

8% Saponin. cml 2.5

The exposure and transfer techniquegremain the' same as in Example I. Apositive image is obtained onthe transferpaper.

' Example III The following coating formula is usedforthe negative emulsion:

A .m n g 15' 10% inert gelatin g 30' 68% aqueous solution of AgNOg ml 2.5 Silver iodide g .,2.5 10% Chrome alum j ml 0.5 8% Saponin ml 5 2.5;

The exposure technique isthe same as in'Example'L. The paper used as the transfer medium is impregnated with the; following solution:

Resorcinol- 3 Sodium sulfite 8 Water and dried before transferxAfter transfer, accordingto Example I, a positive resist appears 'on the transfer paper,

which quickly assumes a dark blue-black colon. Lines and letters of the printed matter aresharply reproduced. The

transfer process may be repeated 35 times after renewed moistening of the negative emulsion.-

Example IV.

Thefollo'wing solutionsis peparedfand designatedpas W 5:

G." Acrylamide- N.N-methylene-bis-acrylamide 7' Water .120

The following coating is. produced on a-rigid paper support: v

Ml. W5 10 10% gelatin solution 35 Silver chloride emulsion (commercial type) 5 After. drying, the-coating in contact with a printed document wasexposed refiexwise for two minutes with a 500 watt photoflood" lamp placed at a distance of 11" from the coating... Following exposure, the coating was placed against a moisttransfer, sheet. fora period of a minute. The transfer sheet was then stripped off and exposed to a light source to polymerize the; transferred. monomeric coating: Thus, adirectcopyor original is formed on thetransfer sheet and an image oppositewin character to:

the original is formed ,on the exposed material.

Modifications, of the invention Will occur to. persons.

skilled in theart. Thus, in lieu of the particular catalysts mentioned in the examples, we may use any of the catalystsj specified above.

Similarly, in lieu of acrylamide,; resort may be had to any of thetlisted polymerizable vinyl monomers. We, therefore, do not intend to be limited in the patent granted except as necessitated by the appended claims.

We claim:

1. A method of photographic reproduction which comprises exposing reflexwise a translucent base carrying a light-sensitive emulsion containing a polymerizable ethylenically unsaturated monomer and a water-soluble radiation-sensitive silver compound as the photopolymerization catalyst and silver iodide in a hydrophilic colloidal carrier to a subject to effect photopolymerization and hardening of the emulsion only in the non-image areas of the subject, moistening the emulsion with water, rolling the emulsion against a transfer sheet containing a sensitizer for silver iodide to effect physical transfer of the unpolymerized parts of the emulsion to the transfer sheet, separating the transfer sheet from the emulsion and exposing the transfer sheet to light to produce a resist containing a silver iodide print-out image.

2. The process as defined in claim 1 wherein the 6 colloidal carrier contains in addition a cross-linking agent.

3. The process as defined in claim 1 wherein the photopolymerization catalyst is a water-soluble, radiation-sensitive, light-sensitive silver compound promoted by an amphoteric metal oxide.

4. The process as defined in claim 1 wherein the monomer and the photopolymerization catalyst are watersoluble.

5. The process as defined in claim 1 wherein the photopolymerization catalyst is silver nitrate.

References Cited by the Examiner UNITED STATES PATENTS 2,716,059 8/1955 Yutzy et al. 96-28 3,038,800 6/1962 Luckey et al 96-114 3,075,907 1/1963 Levinos 96-35 3,091,528 5/1963 Buskes 96-28 NORMAN G. TORCHIN, Primary Examiner. 

1. A METHOD OF PHOTOGRAPHIC REPRODUCTION WHICH COMPRISES EXPOSING REFLEXWISE A TRANSLUCENT BASE CARRYING A LIGHT-SENSITIVE EMULSION CONTAINING A POLYMERIZABLE ETHYLENICALLY UNSATURATED MONOMER AND A WATER-SOLUBLE RADIATION-SENSITIVE SILVER COMPOUND AS THE PHOTOPOLYMERIZATION CATALYST AND SILVER IODIDE IN A HYDROPHILIC COLLOIDAL CARRIER TO A SUBJECT TO EFFECT PHOTOPOLYMERIZATION AND HARDENING OF THE EMULSION ONLY IN THE NON-IMAGE AREAS OF THE SUBJECT, MOISTENING THE EMULSION WITH WATER, ROLLING THE EMULSION AGAINST A TRASNFER SHEET CONTAINING A SENSITIZER FOR SILVER IODIDE TO EFFECT PHYSICAL TRANSFER OF THE UNPOLYMERIZED PARTS OF THE EMULSION TO THE TRANSFER SHEET, SEPARATING THE TRANSFER SHEET FROM THE EMULSION AND EXPOSING THE TRANSFER SHEET TO LIGHT TO PRODUCE A RESIST CONTAINING A SILVER IODIDE PRINT-OUT IMAGE. 